期刊
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
卷 522, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.jmmm.2020.167570
关键词
Magnetic nanoparticle assemblies; Blocking temperature; Monte Carlo simulations; gamma-Fe2O3 core/SiO2 shell morphology; Dipolar interparticle interactions
资金
- Fulbright Foundation
- project Development of Materials and Devices for Industrial, Health, Environmental and Cultural Applications - Operational Programme Competitiveness, Entrepreneurship and Innovation (NSRF 2014-2020) [MIS 5002567]
- European Union (European Regional Development Fund)
- Institute of Bioengineering and Nanotechnology (Biomedical Research Council (BMRC), Agency for Science, Technology and Research (A*STAR), Singapore)
- NanoBio Lab (BMRC, A*STAR, Singapore)
The effect of core size on the magnetic behavior of nanoparticle assemblies was investigated, showing that an increase in magnetic core size results in a shift of the maximum magnetization peak to higher temperatures. The study sheds light on how interparticle distance and magnetic core size influence the behavior of the assembly.
The effect of core size on the magnetic behavior of nanoparticle assemblies of gamma-Fe2O3 core/SiO2 shell morphology is investigated. Long-range magnetostatic interactions are probed in two highly monodispersed experimental test systems of spherical nanoparticles with core diameters of 10 nm and 12.5 nm, and a shell thickness varying from 0 nm (bare particles) to similar to 50 nm. Zero-Field-Cooled magnetization curves are calculated by employing the Monte Carlo simulation technique in a mesoscopic-scale model for the assembly, assuming spin collinearity and coherent spin-reversal mechanisms. Simulation results reproduce the trend in the behavior of the Zero-Field-Cooled magnetization versus T curves in good qualitative agreement with the experimental findings. They also demonstrate that the increase of the magnetic core size results in a shift of the maximum magnetization peak, T-max, to higher temperatures due to enhanced dipolar coupling. The results shed light on how interparticle distance and magnetic core size influence the value of T-max through collective behavior and its transition to a single-particle superparamagnetic blocking temperature, T-B, as the assembly becomes magnetically diluted with increasing shell thickness.
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